SDMSDocID 2009745
L
r : : - " ' ~Purpose: CERCLA Site Inspection
Site: Gila River Indian Reservation51st AvenuePhoenix, ArizonaMaricopa County
She EPA ID Number:
URS Investigators:
Date of Inspection:
Report Prepared By:
Report Reviewed By:
Review Concurrence:
*Report Date: * April 23,1997
Document Control No.: 41.62312.71.33.1878 05.a.1
AZD981621881»
John P. ZwierzyckiGary Floyd
March 22,1996
John P. Zwierzycki
• ChrisLNelSon'
Submitted To: Carolyn DouglasEPA Region, IXSite Assessment Manager
URS Greincr, Inc.Contract No 68-W9-00'S4
ARCS EPA Region IXWA No. 54-27-9JZZ
Table of ContentsSection Page
1.0 Introduction .. 11.1 Apparent Problem 1
2.0 Site Description 22.1 Site Location 22.2 Site Description 22.3 Operational History 22.4 Regulatory Involvement 6
2.4.1 United States Environmental Protection Agency (EPA) 62.4.2 Gila River Department of Environmental Quality 62.4.3 Arizona Department of Environmental Quality 62.4.4 Agency for Toxic Substance and Disease Registry 72.4.5 Arizona Department of Health Services 72.4.6 Bureau of Indian Affairs 7
3.0 Investigative Efforts — 83.1 Previous Sampling 8
3.1.1 Soil Sampling 83.1.2 Air Sampling 11
3.2 EPA Sampling 123.2.1 Purpose and Description of Sampling Event..... 123.2.2 Deviations from Sampling Plan 133.2.3 Discussion of Sample Results 133.2.4 Enzyme Immunoassay Screening 14
4.0 Hazard Ranking System Factors 374.1 Sources of Contamination 374.2 Groundwater Pathway 37
4.2.1 Hydrogeologic Setting 374.2.2 Groundwater Targets 384.2.3 Groundwater Pathway Conclusions 39
4.3 Surface Water Pathway 394.3.1 Hydrologic Setting 394.3.2 Surface Water Targets ., 394.3.3 Surface Water Pathway Conclusions 39
4.4 Soil Exposure and Air Pathways 404.4.1 Physical Conditions 404.4.2 Soil and Air Targets 404.4.3 Soil Exposure and Air Pathway Conclusions 41
5.0 Emergency Response Considerations „ 42
6.0 Summary ~ 43
7.0 EPA Recommendations - 44
8.0 References ~ 45
List of FiguresFigure Page
2-1 Site Location Map 3
2-2 Facility Map 4
3-1 Sampling Zone Map 10
3-2 Sample Location Map: Gila River Indian Reservation 15
3-3 Sample Location Map: Yazzie HomeSite Area 16
3-4 Field Screening Location Map 17
3-5 Sample Location Map: Field Screening Locations Along Airstrip 18
3-6 Sample Location Map: South of the Yazzie Homesite Area 19
3-7 Toxaphene Concentration Map 36
List of TablesTable Page
3-1 Summary of Soil Sample Analysis for Toxaphene: Thomas Homesite.... 11
3-2 Results of Surface Soil Sampling for Organochlorine Pesticides:May 30 and 31, 1996 20
3-2 Results of Surface Soil Sampling for Organochlorine Pesticides:August 15, 1996 31
3-4 Results of Enzyme Immunoassay Screening for Toxaphene:August 15 and 16, 1996 34
4-1 Population Within 4 Miles of GRIR Site : 40
List of Appendices
A Contact Log and Contact Reports
B Site Observation Report
C Photo Log
D Latitude/Longitude Worksheet
E Laboratory Analytical Reports
f \ }_ \ \
1.0 Introduction
Under authority of the Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 (CERCLA) and the Superfund Amendments and Reauthorization Act of 1986 (SARA),
the U.S. Environmental Protection Agency (EPA) has tasked URS Greiner, Inc. (URSG) to
conduct a Site Inspection (SI) of Gila River Indian Reservation located in Maricopa County,
Arizona.
The Gila River Indian Reservation was identified as a potential hazardous waste site and entered
into the Comprehensive Environmental Response, Compensation, and Liability Information
System (CERCLIS) on July 13, 1984 (1). On June 14, 1984, the EPA's Emergency Response Section
was contacted by the Gila River Department of Environmental Quality (GRDEQ) after soil
samples collected from the site indicated the presence of significant concentrations of
pesticides. A Preliminary Assessment (PA) was performed for the EPA in October 1985 by Roy
F. Weston, Inc. The purpose of the PA was to review existing information on the site and its
environs to assess the threats, if any, posed to public health, welfare, or the environment, and to
determine if further investigation under CERCLA/SARA is warranted. After reviewing the PA,
the EPA decided that further investigation of Gila River Indian Reservation would be necessary to
more completely evaluate the site using the EPA's Hazard Ranking System (HRS) criteria. The
HRS assesses the relative threat associated with the actual or potential releases of hazardous
substances from the site. The HRS is the primary method of determining if a site is eligible for
placement on the EPA's National Priorities List (NPL). The NPL identifies sites at which the EPA
may conduct remedial response actions. This SI report is the result of URSG's recent
investigation.
1.1 Apparent Problem
Surface soils at the Gila River Indian Reservation Site are suspected to be contaminated with the
Organochlorine pesticides Toxaphene, DDT, p, p-dichlorodiphenyl-dichloroethylene (DDE), and
DDD and the organophosphate pesticides s,s,s-tributyltrithiophosphate (DEF), ethyl parathion,
and methyl parathion. The amount and extent of pesticide contamination at the former
pesticide container disposal area and the suspected airstrip are unknown. These areas of
potential surface soil contamination represent sources from which further contaminant
migration may occur. Pesticide contamination in the yards of residences near the site may pose a
threat to the health of the residents.
URS Gr*in*r, Inc. Page 1
2.0 Site Description
2.1 Site Location
The Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of
Phoenix, Arizona. The geographic coordinates of the site are 33° 19' 31" North latitude, and 112°
10' 14" West longitude, Township 1 South, Range 2 East, Section 20, Gila and Salt River Baseline
and Meridian (2). The site location is shown on Figure 2-1.
2.2 Site Description
The site occupies approximately 20 acres in a rural area. The site is bordered on the north by the
Gila River Indian Reservation boundary and agricultural land, on the west by a drainage canal, on
the south by a dirt road and agricultural land, and on the east by 51st Avenue.
Buildings now on-site include a double-wide mobile home, and dilapidated buildings.
Historically, buildings on-site included several wooden buildings that had a variety of uses. A
2,357-foot-long dirt airstrip, no longer in use, is present at the site. The presence of a second,
shorter airstrip is suspected (see Figure 2-2). A former pesticide container dumping area is
located east of the 2,357-foot-long airstrip (3). Several concrete-lined drainage ditches are
present on and around the site. Much of the site has been used for the dumping of construction
debris, furniture and appliances, and municipal waste. The site layout is presented on Figure 2-2.
2.3 Operational History
Mr. Bill Taylor, former site operator, stated that the airstrip was first used in 1959 by the Bill
Lewis Crop Dusting Service. The Bill Lewis Crop Dusting Service operated at the site for about 1
year. Between 1970 and 1973, the facility was operated by Taylor Flying Service. In 1973, the
Samply Flying Service of Parker, Arizona, purchased the Taylor Flying Service, and continued to
operate at the site until about 1975. In 1975, the Samply Flying Service relinquished the business
to Mr. Bill Taylor, who then operated the site until 1977. The site was leased by Hudson Farms,
Inc. from 1977 to 1978. The site continued to be used as a crop dusting service until the early
1980s. Historical photographs from 1980 and 1986 indicate that areas outside the airstrip were
recently used as irrigated farmland. Part of the site was leased in 1976 from the Bureau of Indian
Affairs (BIA) by Hudson Farms, Inc. (4).
URS Gr*in*r, Inc. Page 2
Soupo«:USGS Topographic Maps, LaveenQuadrangle, Photorevised, 1973
URS Gr«in*r, Ino.100 California StreetSan Francisco. CA 94 111December 10, 1996
Site Location MapGila River Indian Reservation
Phoenix, Arizona
FIGURE
2-1
Container Disposal»Area
undisturbedcontaining nat
URS Greiner, Inc.100 California StreetSan Francisco, CA 94111
'• December 10,1996
Facility MapGila River Indian Reservation
• Phoenix, Arizona
FIGURE
2-2
The ownership of the site is r_-.iplex. The site location crosses seven allotments (5). Each
allotment is owned by one or more individuals and managed in cooperation with the Gila River
Indian Community and the BIA re_l estate office. The BIA real estate office approves of and
manages leases of the allotments (5, It is not known if areas used as the airstrip at the site were
leased by the crop dusting services.
Figure 2-2 shows the location of Me former pesticide container disposal area. The Gila River
Indian Community investigated < ic site in 1984 and found 50 to 100 empty 5-gallon pesticide
containers. Labels on the containers identified the following pesticides as having been used at
the facility: Azodrin, Toxaphene. methyl-parathion, Lannate-L, DEF-6, Ambush, Bolstar-6, and
Furadan G). Pesticides were J>..»pa ently stored in containers at the site; there is no evidence to
suggest that above-ground or underground storage tanks existed at the site. Empty pesticide
containers were removed from the dumpsite by Mr. Dave Hudson, of Hudson Farms, Inc., who
leased the site from 1977 to 1978 (4).
An emergency response action at the Thomas Homesite portion of the site was conducted by
the EPA Region IX Technical Assistance Team (TAT) (n 1984 (7). The jemetgjKicy response
included the excavation and removal of pesticide-contaminated sou, the chemical and biological
treatment of remaining contaminated soils, and the placement of a soil cap over an area of the
site known as the Thomas Homesite. The majority of prior sampling at the site has been
conducted at the Thomas Homesite and is described in Section 3.1.1. The EPA emergency
response was completed on December 8, 1986 (8).
There is little documentation available presenting the historical waste management practices at
the site. It is believed that most of the hazardous waste at the site was created by spills during the
mixing, loading, and handling of pesticides and herbicides before application to crops. During
the EPA emergency response at the site, buried pesticide containers were located within the
boundaries of the Thomas Homesite. Hazardous wastes excavated by the EPA during the
removal action at the Thomas Homesite were transported to and disposed of at the U.S. Ecology
facility located in Beatty, Nevada (9).
URS Gr*in*r, Ino. Page 5
2.4 Regulatory Involvement
2.4.1 U.S. Environmental Protection Agency
The GRIR site was entered into the CERCLIS databace on July 13, 1984 (1). The site is not listed inthe Resource Conservation and Recovery Informs ion System (RCRIS) database as of February 21,
1995.
The EPA began an emergency response at the Thomas Homesite on July 27, 1984 (10). The
emergency response included relocating Indian families living on-site, and excavating and
removing soils containing concentrations of 'oxaphene greater than 1,000 milligrams per
kilogram (mg/Kg). The remaining soil was chemically and biologically treated and a 6- to 15-inch
soil cap was placed over a portion of the site. The removal action was conducted in response to
an Immediate Removal Action Memorandum by on-scene coordinator Robert Millinaux and was
approved on July 31, 1984 (11).
2.4.2 Gila River Department of Environmental Quality
The Gila River Department of Environmental Quality (GRDEQ) has been involved with the site
since May 17, 1984. At that time, GRDEQ received a complaint from Mr. Joe Thomas regarding
pesticide soil contamination near his home. Mr. Charles Moses of the Gila River Indian
Community Pesticide Office conducted an inspection of the Thomas Homesite and discovered
empty pesticide containers. Mr. Moses collected soil samples to determine if pesticides were
present at the Thomas Homesite. Analysis of soil samples showed the soil was contaminated•
with Ethyl-Parathion, Methyl-Parathion, Toxaphene, and DEF (10). On June 14, 1984, the GRDEQ
contacted the EPA Region IX Emergency Response Section regarding the site to request Federal
assistance (12).
2.4.3 Arizona Department of Environmental Quality
The Arizona Department of Environmental Quality (ADEQ) has not been actively involved with
the investigations at the site. ADEQ does not maintain a file regarding the site.
URS Gr*in*r, (no. Page 6
2.4.4 Agency for Toxic Substance and Disease Registry (ATSDR)
The ATSDR reviewed the medical- and health-related aspects of the site, including results of
blood testing for cholinesterase from 14 of the residents of the site, at the time of the EPA
emergency response. Cholinesterase is a neurotransmitter found in the blood. Blood
cholinesterase levels can be lowered by organophosphate pes\: ;ides, which may result in health
problems (13). According to ATSDR, one adult and o-ie child had slightly depressed
cholinesterase levels, and two children had levels below 56 percent of the normal range. These
results could not be used to show a health effect after a presumed exposure to organophosphate
pesticides because there were no tests taken before the presumed exposure to compare with(14). ATSDR recommended periodic testing of serum cholincsterase levels of site residents.
2.4.5 Arizona Department of Health Services
The Arizona Department of Health Services (ADHS) has been involved with the site-since June
1984. At that time, representatives of ADHS conducted a survey of the site to supplement aerial
photographs taken by the EPA (15). The ADHS, along with the Indian Health Service, conducted
serum cholinesterase sampling and analysis from residents of the Thomas Site.
2.4.6 Bureau of Indian Affairs
The Bureau of Indian Affairs (BIA) has not been actively involved with the investigation of
pesticide contamination at the GRIR site. BIA, however, does keep a file regarding EPA activities
at the site, and has managed leases of the site property (6).
URS Gr*in*r, Ino. Page 7
\ j
)
> 3.0 Investigative Efforts
3.1 Previous Sampling
3.1.1 Soil Sampling
The emergency response action, begun on July 27, 1984, was limited t< a portion of the site
known as the Thomas Homesite. The emergency response action included relocating 19
persons who resided at the Thomas Homesite, and the excavation and removal of highly
contaminated soils. The remaining soils were chemically treated and the S;:e was capped with 6
to 15 inches of clean fill. Initial sampling of soils at the site indicated tibe pfestnce of Toxaphene *
at concentrations as high as 15,000 mg/Kg, as well as lesser concentration of 4,4'-DDE, methyl
parathion, ethyl parathion, and DEF (7). Toxaphene is considered the main contaminant of
concern at the site because it was found in higher concentrations in soil than other pesticides,
and it has a much longer half-life in soil than the organophosphate pesticides previously found at
the site, such as ethyl and methyl parathion, and DEF (16, 17, 18).
In September 1984, further sampling was conducted at the Thomas Homesite. During the
sampling event, 37 locations were sampled by the EPA TAT. Analysis indicated that soils at the
Thomas Homesite contained concentrations of Toxaphene at up to 14,100 mg/Kg, methyl
parathion at up to 8,280 mg/Kg, ethyl parathion at up to 5,830 mg/Kg, and DEF at up to 91.0
mg/Kg (7). Soil samples collected during this investigation were collected before the chemical
and biological treatment activities. Additional monitoring after chemical and biological
treatment, which occurred throughout 1984 and 1985, indicated significantly lower
concentrations of contaminants in soil at the Thomas Homesite (19).
On September 18, 1984, eight soil samples were collected near the airstrip outside of the Thomas
Homesite by OCM Incorporated for Hudson Farms, Inc. Soil samples were analyzed for the
presence of Toxaphene, ethyl parathion, and methyl parathion. Analytical results indicated the
presence of Toxaphene in all soil samples. The amounts of Toxaphene ranged from 3-19 mg/Kg
to 780 mg/Kg. Ethyl parathion was detected in one sample (designated 19776-5A) at 0.12 mg/Kg
(20).
The ereftftient of contaminated soil at the TTjomas HomeSite began to March 1985. The Thomas
Homesite was first tilled to a depth of 1.5 to 2.0 feet below ground surface (bgs) using a tractor
URS Gr«in«r, Ino. Page 8
and plow. The tilling was done to aerate the soil and create a uniform treatment zone. After the
soil tilling was completed, an underground sprinkler system was installed.
After tilling and installing the watering system, 35,000 pounds of sodium hydroxide were added
to the soil. Using a tractor with a fertilizer-spreading attachment, about 200 grams per square
foot were applied to the site. A plow and disc were used to mix the sodium hydroxide into the
soil.
'over 2"iSrjntfiSj During the treatment process, soil was
watered daily and turned weekly using a disc. Sampling results indicated a 45 percent reduction
inToxaphene concentrations after 69 days of treatment. This decrease was suspected to be due
primarily to dechlorination of the more complex components of Toxaphene.
Following the chemical treatment, the Thomas Homesite was then prepared for biological
treatment with anaerobic bacteria. Anaerobic bacteria cultures were applied to the Thomas
Homesite just prior to covering the site with between 6 and 18 inches of clean fill.
To monitor the effectiveness of the chemical and biological treatment of soil at the Thomas
Homesite, a series of soil samples was collected from nine separate sampling zones that were
established on the Thomas Homesite (see Figure 3-1). Sampling zone locations were established
based on geographic features (houses, trees, corrals, etc.) at the Thomas Homesite. Table 3-1
presents the results of analysis from soil samples collected between April 16, 1985 and March 21,
1986. Analytical results showed that chemical and biological treatment of soils significantly
reduced the amount of Toxaphene in each of the sampling zones.
URS Gr*in*r, Inc. Page 9
«r
Not To Scale
URS Gr*in*r, Inc.100 California StreetSan Francisco. CA 94111November 1, 1996
Sampling Zone MapSamples Collected in 1985 and 1986
Gila River Indian ReservationPhoenix, Arizona
FIGURE
3-1
uTable 3-1
Summary of Soil Sample Analysis for ToxapheneThomas Homesite
Gila Indian Reservation(mg/Kg)
Zone
1
2
3
4
5
6
7
8
9
•4.
4/16/85
418
186
525
28.6
90.9
366
194
238
610
5/1/85
450
140
450
140
76.1
290
390
230
550
5/22/85
385
135
420
110
52.3
1,900
68
295
400
6/24/85
330
105
270
62
30.7
470
79.5
130
180
7/1/85
225
145
115
97.5
55.5
83
63
110
130
8/15/85
150
24
160
98
34
56
N/A
180
150
10/7/85
102
339
49-5
62.7
27.5
36.3
26.2
46.2
70.7
10/21/85
208
53
63
27
N/A
102
N/A
N/A
38
3/21/86
80.4
53.0
41.4
30.0
3.12
25.3
1.55
34.5
33X /^? S*^*Jf(i« Al*fJJ ' SltTO+S-AlOi* lAnt^Asjsf-st '/O —
On July 11, 1994, Mr. Adrian HendricKsVthe Pesticide Control Officer oT*the Department of Land
and Water Resources for the Gila River Indian Community, collected three soil samples from the
Yazzie Homesite. Soil samples analyzed by the Arizona State Agricultural Laboratory indicated
the presence of Toxaphene at up to 38 mg/Kg, and DDE at up to 1 mg/Kg. Soil samples were
collected from a depth of 3 feet bgs (21).
3.1.2 Air Sampling
In October 1985, three air samples were collected from the Thomas Homesite as part of an
ongoing monitoring program of contaminants at the site by the EPA. Of these three samples,
two were collected with charcoal tubes, and one sample was collected with an air filter. All
samples were analyzed for Toxaphene by a technique called gas chromatography.. Analysis of air
URS Grciner, Ino. Page 11
samples did not indicate the presence of Toxaphene in air at or above the analytical detection
limit of 0.002 milligrams per cubic meter (mg/m3) at the Thomas Homesite (22).
3.2 EPA Sampling
•Two sampling events were conducted by URSG for the EPA at the GRIR site. Surface soils were
collected during both sampling events. Samples were analyzed for Organochlorine and
organophosphate pesticides according to the Field Sampling Plan, and the Addendum to the
Field Sampling Plan (23, 24).
3.2.1 Purpose and Description of Sampling Event
Under the direction of the EPA, the URSG team prepared a Field Sample Plan and Field Sample
Plan Addendum to collect surface soils at and around the GRIR site (23, 24). This plan was
reviewed by the EPA's Quality Assurance Management Section and Planning and Assessment
Branch. The Sample Plan was approved by the EPA in August 1996.
Sampling of the GRIR site by URSG was conducted to identify the presence of Organochlorine or*
organophosphate pesticides in surficial soil and to determine the extent of surficial soil
contamination. Samples were collected from the site in May and August 1996.
A total of 58 surficial soil samples, including four duplicates and three background samples, were
collected from on- and off-site locations. Sample materials were collected using a dedicated
metal trowel and homogenized in a paper paint bucket, then placed into 8-ounce or 16-ounce
glass jars.
Before shipment to the laboratories, samples were custody-sealed, entered on a Chain-of-
Custody, double-bagged, and placed in a cooler with ice for shipment to laboratories. Samples.
collected during the sampling event were analyzed for Organochlorine pesticides by Contract
Laboratory Program Analytical Services (CLPAS), and for organophosphate pesticides? by RAP
methods. Data validation was conducted by Lockheed Martin's Environmental Services
Assistance Team.
The first soil sampling event was conducted on May 30 and 31, 1996. This sampling event
included the collection of 50 surface soil samples, including three duplicates and two background
samples. Samples were collected using a triangular grid system, in order to generate a more
representative data set given a defined number of sampling points. Three soil samples were
submitted as matrix spike duplicates. Of these 50 surface soil samples, five were collected from ;
the former Thomas Homesite, 20 were collected in a triangular grid pattern from areas south of
URS Greiner, Ino. Page 12
othe Thomas Homesite, three were collected from an area believed to have been used as an
airstrip, located south of both the Thomas Homesite and Yazzie Homesite, three were collected
from the former pesticide container disposal area, and eight were collected from along the
airstrip based on field screening results. One sample (SS-29) was collected near a well located
approximately one-quarter mile west of the site, and four samples were collected from a
residential area located east of 5ls Avenue (see Figures 3-2, 3-3, 3-4, and 3-5). Soil samples
collected from along the airstrip were selected based on the results of field screening using
enzyme immunoassay (EIA) test kits. LaJiQraiory confirmation samples w€re"£Mteaec> ftdfr lac
of Toxaphene, and two screening locations that indicated tow Toxaphene concentrations. *
The second soil sampling event wa? conducted on August 15, 1996. This sampling event included
the collection of eight soil samples, including one duplicate and one background sample. Soil
samples collected from the site were selected based on the results of field screening of 60
locations using enzyme immunoassay test kits. Field screening and sampling locations are
presented in Figure 3-6.
3.2.2 Deviations from Sampling Plan
URSG collected an additional five surficial soil samples from the Thomas Homesite portion of the
site as part of the first round of soil sampling. The additional soil samples were collected at the
request of the EPA Site Assessment Manager. These samples were collected from the soil cap
that was placed on the Thomas Homesite as part of EPA's emergency response action and were
designated SS-42 through SS-46.*
3.2.3 Discussion of Sample Results
Analytical results of soil samples collected from areas south of the Thomas Homesite showed the
presence of Organochlorine pesticides at levels greater than three times background
concentration (see Tables 3-2, 3-3, and 3-4, and Figure 3-7). Organophosphate pesticides were
not found at soils. Sampling results, in combination with EIA field screening results, indicate that
soils contaminated with Organochlorine pesticides have not migrated significantly from the
northeastern end of the airstrip, where it is believed that crop-dusting planes were fueled and
loaded with pesticides, and possibly washed. rToxaphene concentrations at the sue ranges from
not detectable to 830 pprrO Sampling results cannot be compared to prior sampling results,
either because samples were not collected from the same area, or clean, imported fill material
had been brought to the sampling location.
URS Gr*iner, Ino. Page 13
Lj )Data quality objectives established in the sample plan were generally met, although some minorinconsistencies in precision and accuracy did exist (23). Analytical data packages, includingexplanations of data qualifiers, can be found in Appendix E, Laboratory Analytical Reports.Overall, there was acceptable correlation between standard and duplicate samples.
3.2.4 Enzyme Immunoassay Screening
The enzyme immunoassay test is a colorimetr c test. The amount of Toxaphene in a given
sample is inversely proportional to the reading from a photometer: the greater the photometerreading, the less Toxaphene in the sample.
During the May 1996 Sampling Event, fu "d .creening results indicated concentrations ofToxaphene in excess of 100 ppm along the for Tier airstrip at the site, and near a well locatedsouthwest of the site. A portion of the field screening samples was not diluted prior to
immersion into the enzyme tube; therefore, the standards for comparison of these samples
represented 0.5, 2, and 10 ppm; whereas with the other samples, the standards represent 5, 20,and 100 ppm Toxaphene. This resulted in EIA results that were biased high. Nine soil sampleswere collected for laboratory confirmation of the field screening results. Laboratory results(presented in Table 3-2) indicated inaccuracies in the field screening results. Some uncertaintyregarding the results is present because the enzyme immunoassay test was conducted attemperatures exceeding the recommended 60 to 80°F (degrees Fahrenheit). Additionally,photometer results from prepared standards indicate a level of accuracy outside manufacturer-
specified control limits. All three standards were found to give absorbencies substantially higher
than the manufacturer's stated limits. It is not clear to what extent the high ambient temperature
(100°F) may have contributed to this. The manufacturer states that the kits are designed for an
operating range of 60 to 80°F; however, due to the standards falling outside the prescribed limits,
URSG regards the screening results as very qualitative.
During the August, 1996 Sampling Event, field screening results indicated limited concentrationsof Toxaphene in areas south of the Yazzie Homesite. The results of the field screening and
laboratory analysis for those samples sent for laboratory confirmation are presented in Table 3-4. Laboratory confirmation sampling indicates a poor correlation with field screening results;
however, field screening results may be used qualitatively.
URS Greiner, Inc. Page 14
Irrigation Ditch
= Grid Sampling Area
= Area field screened withconfirmation samples collectedbased on field screening results
• = Discrete sample point
Two soil samples for field screeningwere also collected from an areaapproximately 0.25 mile west of thesite near an agricultural well that mayhave been used as a pesticide-mixing area
e background SS-40-located approximately 0.5mile west of the site
e background SS-41located approximately 0.5mile east of the site D *• eSS-3
Yazzie Homesite
Not To Scale
URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27,1997
Sample Location MapGila River Indian Reservation
Phoenix, Arizona
FIGURE
3-2
Airstrip
<?-.« •8"SS"-13*
is-19
Mobile^Home
/ SS-17 ^sa-ia /"^S^ S£05 SS-0
1 \ I \ / \ I/ \ I \ I
t \ I \ I\ I \ /ss>11 \ / \ i
®- (j£- SS-07 0 SS-03
\ / \ / \\ / \ /
/ \ / \ /
*£s£-18_ KS5."1i X. §?'1° \L _°^
\ ^ x // x / \ / \ / N /
/ v / \ / \ / \ f
/ ^ Yazzie/Homesite \ / \ \ /
/' N N / \/ • \ ' \ /
Thomas Homesite
151st AvenuNot To Seal*
URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997
Sample Location MapYazzie Homesite Area
Gila River Indian ReservationPhoenix, Arizona
FIGURE
3-3
FS-24
O = Field Screening location
I
URS Greiner, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997
Field Screening Location MapSouthwestern End of AirstripGila River Indian Reservation
Phoenix, Arizona
FIGURE I
3-4
Field Screening locations FS-26 and FS-27were located near a well approximately 0.25mile west of the southern end of the airstrip.
FS-2
lAirstripl
YazzieHomesite Not To Scale
URS Greiner, Ino.100 California StreetSan Francisco, CA 941 1 1January 27, 1997
Sample Location MapField Screening Locations Along Airstrip
Gila River Indian ReservationPhoenix, Arizona
FIGURE
3-5
Continue grid patternup to the dirt road.
_ _ ?18 ^fSlf4 ^fSi° -qf8:36 -QfS:32 ^ ps-28
/ X / \ I \ / x / \ X X/ X ' X / \ / \ / X / X
> X X / \ / \ X X X X
\ ' X / X / \ / X/ X '
' fsl°_ _ -^. L8!6 - _ -C/FS^2 - - - 'F&38. -N
/x/ x / x / \\ \ \ /°~X !\ / N
\ 'FS-SO \6SS-19' (collected
X / 5/96)v /
XFS-49
x / s ' N ' sX X X X
'FS-41 \XFS-37 v/PS'33
^ -H\ / X / X
v I \ ' \
> \ / x / • x xX / v / . /
FS-51
x
\ x \ x
x
q FS-29
' \\
(collected^ 5/96)•OSS-20
151st Avenue*Not To Scale
URS Grein.r, Ino.100 California StreetSan Francisco, CA 94111June 19, 1996
Sample Location MapSouth of the Yazzie Homesite Area
Gila River Indian ReservationPhoenix, Arizona
FIGURE
3-6
Table 5-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BrlC(Lindane)HeptachlorAldrinHepiachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndrineEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-117 U17 U17 U17 U
17 U17 U
1700 NJ
17 U1300 J4900
1700 U1700 U33 U
1700 U
1700 U1700 U33 U
1700 U17 U
1300 NJ
350000330 U680U330 U330 U330 U330 U330 U
SS-1D17 U17 U17 U17 U
17 U17 U
1400 NJ
17 U1000J
5300 NJ1700 U1700 U33 U
1700 U
1700 U1700 U33 U
1700 U17 U
1300 NJ
310000330 U680U330 U330 U330 U330 U330 U
SS-2170 U170 U170 U170 U
170 U170 U
310 NJ
170 U330 U67000860 NJ1400 NJ330 U1300
4400 U1700 U330 U330 U170 U
680 NJ
1200003300 U6800U3300 U3300 U3300 U3300 U3300 U
SS-3860U860U860U860U
860 U860 U860 U
860 U1700 U3700 NJ1700 U1700 U1700 U1700 U
1700 U8600 U1700 U1700 U1700 U
3900 NJ
310000 J17000 U34000 U17000 U17000 U17000 U17000 U17000 U
SS-42.0 U2.0 U2.0 U2.0 U
2.0 U2.0 U2.0 U
2.0 U3.9 U
250 NJ3.9 U91 NJ3.9 U36 NJ
260 NJ20 U3.9 U3.9 U2.0 U
36
660039 USOU39 U39 U39 U39 U39 U
RID
———
23,000
39,0002,3001,000
47,0003,900
—23,00047,000..._-..
39,000390,000
——...
___
...1,6001,6001,6001,6001,6001,6001,600
CSRC100360
—490
1403870
—401,900
——
2,700---
1,900
—— -
—...
— _ —
58083838383838383
Ta ,e 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31,1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin keioneEndrin aldehydealpha -Chiordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Arocior-1242Aroclor-1248Aroclor-1254ArocIor-1260
SS-0517 U17 U17 U17 U
17 U17 U
650 NJ
17 U930 NJ3600
1700 U1600 NJ240 NJ1700 U
33 U170 U33 U
1400 NJ17 U
1200
190000330 U670 U330 U330 U330 U330 U356 U
SS-062.1 U2.1 U2.1 U2.1 U
2.1 U2.1 U2.1 U
2.1 U4.1 U
2100 NJ1100NJ980 NJ520 NJ1100
4.1 LI640 NJ4.1 U
470 NJ2.1 U •
360 NJ
6900041 U83 U41 U41 U41 U41 U41 U
SS-0717 U17 U17 U17 U
17 U17 U
360 NJ
17 U900 NJ
2100 NJ440 NJ1000 NJ320 NJ
900
33 U170 U33 U33 U17 U
610
76000330 U680U330 U330 U330 U330 U330 U
SS-082.3 U2.3 U2.3 U2.3 U
2.3 U2.3 U2.3 U
2.3 U600 NJ2000 NJ1000 NJ960 NJ510 NJ
990
4.4 U23 U4.4 U660
2.3 U
420
6500044 U90U44 U44 U44 U44 U440
SS-0917 U17 U17 U17 U
17 U17 U
200 NJ
310 NJ96 NJ
1200 NJ1700 NJ1700 U33 U
1600 NJ
33 U2500 NJ
33 U130017 U
1100 NJ
250000330 U670 U330 U330 U330 U330 U330 U
RID
———
23,000
39,0002,3001,000
47,0003,900
—23,00047,000
—~~~
39,000390,000
—...
— — -
___
—1,6001,6001,6001,6001,6001,6001,600
CSRci100360
—490
1403870
—401,900
——
2,700
— — —
1,900—---
—"""
...
58083838383838383
Table 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-09D17 U17 U17 U17 U
17 U17 U
1700 U
17 U1200 NJ3000 NJ1700 U33 U33 U
1700 U
33 U170 U33 U
1700 U17 U
1400 NJ
470000330 U670 U330 U330 U330 U330 U330 U
SS-101.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U930
3.3 U250 NJ
3.3250 NJ
3.3 U160
3.3 U17 U3.3 U '
160 J
1.7 U51 NJ1200033 U67 U33 U33 U33 U
SS-111.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U
130 NJ
1.7 U3-3 U
1500 NJ520 NJ700 NJ3.3 U
350 NJ
1700 U760 NJ3-3 LJ180 NJ1.7 U
520
7800033 U67 U33 U33 U33 U33 U33 U
SS-121.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U
903.3 U
8.9 NJ3.3 U3.3 U
3.3 U17 U3.3 U3.3 U1.7 U
1.7 U
79033 U67 U33 U33 U33 U33 U.33 U
SS-131.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U790
3.3 U65 NJ3.3 U
22
3.3 U17 U3.3 U3.3 U1.7 LJ
21 NJ
480033 U67 U33 LJ33 U33 U33 LJ33 U
RID
——...
23,000
39,0002,3001,000
''7,0003.^3...
23,00047,000...
— - —
39,000390,000
...
...
— — —
— — —
—1,6001,6001,6001,6001,6001,6001,600
CSRC100360
—490
1403870
...40
l,9uO
—...2,700
-_-
1,900.........
— - —
*""**
58083838383838383
Tabic 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansul fate4,4'-DDTMcthoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242 .Aroclor-1248Aroclor-1254Aroclor-1260
SS-142.0 U2.0 U2.0 U2.0 U
2.0 U2.0 U2.0 U
2.0 U4.0 U1200
420 NJ430 NJ320 NJ220 NJ
4.0 U20 U4.0 U4.0 U2.0 U
200
3800040 U81 U40 U40 U40 U40 U40 U
SS-1517 U17 U17 U17 U
17 U17 U2900
17 U1600 NJ
33 U1700 LJ1700 U33 U
1700 U
1700 U1700 LJ33 U33 U17 U '
1700 U
830000330 U670 U330 U330 U330 U330 U330 U
SS-161.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U10 NJ160
3.3 LJ29 NJ21 NJ38 NJ
3-3 LJ17 U3.3 U22 NJ1.7 U
16
240033 LJ67 U33 U33 U33 U33 U33 U
SS-173-8
2.1 U2.6 NJ2.1 U
2.1 U2.1 U6.2 NJ
8.6 NJ35 NJ580
21 NJ48 NJ31 NJ160 NJ
4.1 U64 NJ15 NJ16 NJ
5.3 NJ
3-3 NJ
1100041 U83 LJ41 U41 U41 U41 U41 U
SS-17D3.4
2.4 NJ5.4 NJ
2.5
2.0 U2.0 U18 NJ
23 NJ130J
780 NJ530 NJ400 NJ250 NJ530 NJ
3.8 U270 NJ39 NJ50 NJ57 NJ
9.5 NJ
3900038U78 U38U38U38U38U38LJ
RtD
———
23,000
39,0002,3001,000
47,0003,900...
23,00047,000..."""
39,000390,000
...
...
...
...
—,600,600,600,600,600
1,6001,600
CSRC100360
490
1403870
...40
1,900......
2,700"•""• *'
1,900......
—...
""".
58083838383838383
Tabtc 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
Analyte
Alpha-BHCBeta-BHCDella-BI 1Cgamma-BHC(Lindane)1 IcptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4/r-DDDEndosulfansulfatc4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha-Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-18
1.8 U1.8 U1.8 U1.8 U
18U18U18U
7 2 N J13 NJ110
13 NJ42
88NJ35LJ
17 NJ18 U
35NJ35LJ31NJ
60NJ
700J35 U72 U35 U35 U35 U35 UJ5u
SS-19
17U17U17LJ17U
17LJ17U
10
21 NJ37 NJ
885938
31 NJ67 NJ
92 NJ17 U33LJ46 NJ -11 NJ
24 NJ
2600 J33 U68U33 U33 LJ33 U33 U33 LJ
SS-20
1.7 U17U17LJ1 7 U
17LJ17U1.7 U
1 7 U99NJ
5018
38 NJ33U12 NJ
26 NJ17 U33U33LJ1 7 U
93
760J33 LJ68 LJ33 U33 U33 U33 U33 U
SS-21(FS-16)1.7 U1 7 U17U1 7 U
1 7 U17LJ17LJ
1 7 L J3 3 U
5033LJ
2833U3 3 U
3 3 U17 U33LJ33U17U
17LJ
60033 LJ68 LJ33 U33 LJ33 U33 U33 U
SS-22(FS-17)1 7 U1 7 U1 7 L J1 7 L J
1 7 U17U20 NJ
40 NJ52 NJ62065 J160J51
77 NJ
94 NJ17 LJ16 NJ33LJ18 NJ
28 NJ
3100J33 LJ68 LJ33 U33 U33 U33 LJ33 U
RID
—...
—23,000
39,0002,3001,000
47,0003,900
—23,00047,000
——•• —
39,000'XJ.OOO...
—...
...
—1,6001,6001,6001,6001,6001,6001,600
CSRC
100360...
490
1403870
...40
1,900......
2,700"""
1,900—
i-""""""
""""
58083838383838383
Tab,.. 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
Analyle
Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4, 4 '-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-23(FS-18)2.0 U2.0 U
11 LNJ2.0 U
2.0 U2.0 U2.0 U
11 NJ23 NJ190
56 NJ96'
27 NJ15 LNJ
79 NJ20 U3.9 U3.9 U
6.8 L NJ
9.8 NJ
2700 J39 U79 U39 U39 U39 LJ.39 LJ39 LJ
SJ>-24(FS-19)1.7 U1.7 U1.7 U1.7 LJ
1.7 U1.7 U1.7 LJ
19 NJ9.0 NJ110056 NJ
180 NJ37 NJ79 NJ
340 J17 U51 NJ96 NJ -5.5 NJ
15 NJ
6400 J33 LJ67 U33 U33 U33 U33 U33 LJ
SS-25(FS-21)1.7 U1.7 U1.7 LJ1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U3.3 U3-3 U3.3 LJ3.3 U3.3 U
3.3 U17 U3.3 U3.3 U1.7 U
1.7 U
170 U33 U67 U33 U33 U33 U33 U33 U
SS-26(FS-22)2.1 U2.1 LJ2.1 U2.1 U
2.1 LJ2.1 U2.1 U
2.1 U4.1 LJ
284.1 U4.1 U4.1 LJ4.1 U
4.1 U21 LJ4.1 U4.1 U2.1 U
2.1 U
210 U41 LJ84 LJ41 U41 U41 U41 U41 U
SS-27(FS-23)1.7 LJ1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 LJ
1.7 LJ3.3 LJ
393.3 U12 NJ3.3 LJ3.3 U
3.3 U17 U3.3 LJ3.3 U1.7 U
1.7 U
420 J33 U67 U33 U33 U33 U33 U33 U
RID
...
...
—23,000
39,0002,3001,000
47,0003,900...
23,00047,000
—— — —
39,000390,000
—...•**•"
— — —
—1,6001,6001,6001,6001,6001,6001,600
CSRC
100360...
490
1403870
—40
1,900—
—2,700— — •»
1,900—...
—~~—
...
-* It83838383838383
/"*
Tabie 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
Anaiyte
Alpha-BHCBeta-BHCDelta-BHCganima-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221ArocIor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-28(FS-24)1.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U1.7 U110
3-3 LJ19
3.3 LJ3.3 U
3.3 U17 LJ3.3 LJ3.3 LJ1.7 U
1.7 U
490J33 U68U33 LJ33 U33 U33 U33 U
SS-29(FS-27)2.0 LJ2.0 U2.0 U2.0 LJ
2.0 U2.0 U2.0 LJ
2.0 U4.0 U110
4.0 LJ17
4.0 U4.0 U
4.0 LJ20 U4.0 U4.0 LJ •2.0 U
2.0 LJ
460 J40 U81 U40 U40 U40 U40 U40 U
SS-30
1.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 LJ
1.7 U3-3 LJ
5.23.3 U6.8
3.3 U3-3 U
3.3 LJ17 U3.3 U3.3 U1.7 U
1.9
200J33 LJ68U33 U33 U33 U33 U33 U
SS-31
1.7 U1.7 LJ
121.7 U
1.7 U1.7 U44 NJ
120 NJ70 NJ1100
120 NJ330
65 NJ230 NJ
170 NJ17 U41 NJ110NJ58 NJ
88 NJ
6200 J33 LJ67 U33 U33 U33 U33 U33 U
SS-32
1.7 U1.7 U1.7 U1.7 U
1.7 LJ1.7 LJ10 NJ
1.7 U3.3 LJ
363-3 U
403-3 LJ
20
3.3 LJ17 LJ3-3 U3.3 U1.7 U
9.8 NJ
980J33 U67 U33 U33 U j33 U33 U33 U
R\b
——...
23,000
39,0002,3001,000
47,0003,900...
23,00047,000...
- — —
39,000390,000
...
—""*"
...
—1,6001,6001,6001,6001,6001,6001,600
CSRC1
100360...
490
1403870
...40
1,900
——
2,700...
1,900......
—"""""
...
58083838383fc: I8383
~ 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4, 4 '-DDEEndirneEndosulfan II4,4'-DDDEndosullansulfate4,4'-DDTMethoxychlorEndrin kctoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-32 D2.1 U2.1 U2.1 1)2.1 U
2.1 U2.1 U19 NJ
10 NJ25 NJ
6725 NJ
922852
49 NJ21 U4.1 U29 NJ10 NJ
22 NJ
2200 J41 U84 U41 U41 U41 U41 U41 U
SS-331.7 U1.7 U1.7 U1.7 LJ
1.7 U1.7 U
11
20 NJ50 NJ280
57 NJ140
34 NJ3.3 LJ
54 NJ17 U14 NJ3.3 LJ
9.7 NJ •
22 NJ
2300 J33 U67 LJ33 LJ33 U33 U33 LJ33 U
SS-342.4
1.7 U1.7 LJ1.7 U
1.7 U1.7 U1.7 U
4.6 NJ8.9 NJ
30016 NJ56
5.7 NJ3.3 U
42 NJ17 U3.3 U3.3 LJ1.7 U
4.2 NJ
990J33 U67 U33 U33 U33 U33 U33 U
SS-352.5 NJ
.7U
.7LJ
.7U
.7U
.71)
.7LJ
11 NJ19 NJ300
23 NJ64
12 NJ3.3 U
42 NJ17 U3-3 LJ3.3 LJ1.7 U
10 NJ
990J33 U68U33 LJ33 U33 U33 U33 U '
SS-361.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 LJ
1.7 U3.3 LJ
124.8 NJ
163.3 LJ3.3 LJ
4.8 NJ17 LJ3.3 U3.3 U1.7 U
1.9 NJ
350 J33 U67 LJ33 U33 U33 U33 U33 U
RID
———
23,000
39,0002,3001,000
47,0003,900~.
23,00047,000..."*"*•
39,000390,000
...
...
— — «
_ _ _
1,6001,6001,6001,6001,6001,6001,600
CSRd100360
—490
1403870
—401,900
——2,700
— — —
1,900........."""""
"*""
58083838383838383
3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
Analyte
Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan 114,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-37
1.8 U1.8 U1.8 U1.8 U
1.8 U1.881.8 U
1.8 U5.334
3.4 U19 NJ3.4 U3.4 U
4518 U3.4 U
131.8 U
3.6
91034U69 U34U34U34U34U34U
SS-38
1.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U
613.3 U3.3 U3-3 U3.3 U
7.4 NJ17 U3.3 U3.3 U1.7 U
1.7 U
240 J33 U67 U33 U33 U33 U33 U33 U
SS-39
2.4 U2.4 U2.4 U2.4 U
2.4 U2.4 U2.4 U
2.4 U4.7 U
124.7 U8.9 NJ4.7 U4.7 U
2524 U4.7 U4.7 U2.4 U
2.4 U
53047 U96U47 U47 U47 U47 U47 U
SS-40background
1.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 U3.3 U3.3 U3.3 U3.3 U3.3 U
3-3 U17 U3-3 U3.3 U1.7 U
1.7 U
87 LJ33 U68U33 U33 U33 U33 U33 U
S&41background
2.3 U2.3 U2.3 U2.3 U
2.3 U2.3 U2.3 U
2.3 U4.5 U4.5 U4.5 U4.5 U4.5 U4.5 U
4.5 U23 U4.5 U4.5 U2.3 U
2.3 U
230 U45 U92 U45 U45 U45 U45 U45 U
RID
———23,000
39,0002,3001,000
47,0003,900
—23,00047,000
—— — «•
39,000390,000
...
—._.
-— •
—1,6001,6001,6001,6001,6001,6001,600
cMci
100360
—490
1403870
—401,900
——2,700->•*.
1,900
———~..
...
58083838383838383
Table 3-2Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesMay 30 & 31, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
AnalyteAlpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorEpoxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansulfate4,4'-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254Aroclor-1260
SS-422.1 LJ2.1 U2.1 U2.1 U
2.1 U2.1 U2.1 U
2.1 U4.0 LJ
344.0 U5.0 NJ4.0 U4.0 U
2021 U4.0 U4.0 U2.1 U
2.1 LJ
49040 U82 U40 U40 U40 U40 U46 U
SS-431.7 LJ1.7 LJ1.7 U1.7 LJ
1.7 U1.7 LJ12 NJ
1.7 U3.3 U
280 NJ3.3 U62 NJ3.3 U3.3 U
120 NJ17 U3.3 U
485U '
23 NJ
380033 U68U33 LJ33 LJ33 U33 U33 U
SS-441.7 LJ1.7 U1.7 LJ1.7 U
1.7 LJ1.7 U1.7 U
1.7 U3.3 U
813.3 LJ10 NJ3.3 U3.3 U
15 NJ17 U3-3 LJ3.3 LJ1.7 U
1.7 LJ
74033 LJ68U33 LJ33 U33 U33 U33 U
SS-451.7 LJ1.7 U1.7 U1.7 LJ
1.7 LJ1.7 U69 NJ
30 NJ120
280 NJ340 NJ440 NJ210 NJ3-3 U
850 NJ510 NJ75 NJ150 NJ35 NJ
110NJ
1700033 U67 LJ33 LJ33 LJ33 U33 U33 U
SS-461.7 U1.7 U1.7 LJ1.7 U
1.7 LJ1.7 U1.7 LJ
1.7 LJ120
3.3 U17 NJ3.3 LJ3.3 LJ24 NJ
17 U3.3 U3.3 U1.7 LJ1.7 U
1100
33 U67 U33 LJ33 LJ33 U33 LJ33 U33 LJ
RID...
—...23,000
39,0002,3001,000
47,0003,900
—23,00047,000
—— — —
39,000390,000
—...***"""
•__
—1,6001,6001,6001,6001,6001,6001,600
CSRC100360...
490
1403870
—401,900...
—2,700
--•
1,900
—......
«•— —
-•-
58083838383838383
Notes:RfD Reference Dose Screening Concentration
CSRC Cancer Risk Screening Concentration
U The analyte was analyzed for, but was not detected above the reported sample quantitation limit.
L The results fall below the Contract Required Quantitation Limit. Results are estimated and are consideredqualitatively acceptable but quantitatively unreliable due to uncertainties in the analytical precision near the limitof detection.
R The sample results are rejected due to serious deficiencies in the ability to analyze the sample and meet qualitycontrol criteria. The presence or absence of the analyte cannot be verified.
LJJ The analyte was not detected above the reported sample quantitation limit; however, the reported quantitationlimit is approximate and may or may not represent the actual limit of quantitation necessary to accurately andprecisely measure the analyte in the sample.
J The analyte was positively identified; the associated numerical value is the approximate concentration of theanalyte in the sample.
NJ Hie analysis indicates the presence of an analyte that has been "tentatively identified" and the associatednumerical value represents its approximate concentration.
NO QUALIFIERS indicate that the data are acceptable both qualitatively and quantitatively.
3-3Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesAugust 15, 1996
Concentrations in Micrograms per Kilogram (parts pc. ^'"-r-j)
Analyte
Alpha-BHCBcta-BI 1CDelta-BHCgamma-UrlC(Lindane)HeptachlorAldrinHeplachlorEpoxideEndosulfan 1Dieldrin4,4'-DDEEndirneEndosulfan II4,4'-DDDEndosulfansullate4, 4 '-DDTMethoxychlorF.ndrin ketoneEndrin aldehydealpha -Chlordanegamma-ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248Aroclor-1254ArocIor-1260
SS-1(FS-28)
3.91.8NJ
2.01.5 NJ
1.7 U1.7 U1.7 U
1.7 LJ3.3 LJ260
9.9 NJ3.3 U3.3 LJ
12
30 NJ17 U3.3 LJ3.3 LJ1.7U
1.7 LJ
370 J33 LJ68U33 LJ33 U33 U33 LJ
. i3U
SS-1D(FS-28)
3.61.6 NJ
1.81.4 J
1.7 U1.7 U1.7 U
1.7 U3.3 U230
5.0 NJ3.3 U13 NJ
2.9 NJ
20 NJ17 LJ
2.6 NJ3.3 U •1.7 U
1.7 LJ
100 J33 LJ66U33 U33 U33 U33 LJ33 U
SS-2(FS-30)
2.11.7 U1.6NJ1.7 U
1.7 U1.7 U1.7 LJ
2.4 NJ3.3 LJ180 NJ43 NJ3-3 U3.3 U
49
45 NJ17 U16 NJ3.3 LJ1.7 U
6.7 NJ
1400 J33 U66U33 LJ33 U33 U33 LJ33 U
SS-3(FS-33)
2.01.7 LJ1.4 NJ1.7 LJ
1.7 U1.7 LI1.7 LJ
1.7 U3.2 U180
14 NJ3.2 U3.2 U3.2 U
19 NJ17 U
4.9 NJ12 NJ1.7 U
3-6 NJ
390 J32 U66LJ32 U32 U32 U32 U32 U
SS-4(FS-37)8.4 U8.4 U8.4 LJ8.4 LJ
8.4 U8.4 U8.4 LJ
8.4 LJ16 LJ260
48 NJ16 LJ16 U16 U
84 U16 LJ16 U
8.4 LJ8.4 LJ
1500 J
160 U330 LJ160 LJ160 U160 U160 LJ160 LJ160 LJ
RtD
———
23,000
39,0002,3001,000
47,0003,900...
23,00047,000...-"""
39,000390,000
...
—— • —
--"*
—1,6001,6001,6001,6001,6001,6001,600
CSRC
100360...490
1403870
...40
1,900...
—2,700...
1,900......
—...
"""*
58083838383838383
Table 3-3Gila River Indian Reservation
Results of Surface Soil Sampling for Organochlorine PesticidesAugust 15, 1996
Concentrations in Micrograms per Kilogram (parts per billion)
Analyte
Alpha-BHCBeta-BHCDelta-BHCgamma-BHC(Lindane)HeptachlorAldrinHeptachlorF.poxideEndosulfan IDieldrin4,4'-DDEEndirneEndosulfan 114,4'-DDDEndosulfansulfate4, 4 '-DDTMethoxychlorEndrin ketoneEndrin aldehydealpha -Chlordanegamma -ChlordaneToxapheneAroclor-1016Aroclor-1221Aroclor-1232Aroclor-1242Aroclor-1248ArocIor-1254Aroclor-1260
SS-5(FS-38)8.4 U8.4 U8.4 U8.4 U
8.4 LJ8.4 U8.4 U
8.4 U16 U110
16 U16 LJ16 U16 U
16 U84 U16 U16 U8.4 U
8.4 U
390J160 U330 U160 LJ160 U160 U160 LJ160 LJ
SS-6(FS-70)1.7 U1.7 U.7U.7U
.7LJ
.7LJ
.7U
1.7 U3.2 U
4.5 NJ2.3 NJ5.9 NJ4.3 NJ3.7 NJ
1.6NJ17 U3-2 U3.2 U •1.7 LJ
1.7 U
69 J32 U68U32 U32 U32 U32 LJ32 U
SS-7background
1.7 U1.7 U1.7 U1.7 U
1.7 U1.7 U1.7 U
1.7 U3.3 LJ3.3 LJ3.3 LJ3.3 U3.3 LJ3.3 LJ
3.3 LJ17 U3.3 LJ3-3 LJ1.7 LJ
1.7 LJ
170 U33 U66 U33 U33 LJ33 U33 LJ33 U
RID
———
23,000
39,0002,3001,000
47,0003,900...
23,00047,000
—— -
39,000390,000
—
—
---
—1,6001,6001,6001,6001,600.1,6001,600
CSRC
100360
—490
1403870
—401,900......
2,700
1,900...
——~"
•"""
58083838383838383
Notes:RfD Reference Dose Screening Concentration
CSRC Cancer Risk Screening Concentration
U The analyte was analyzed for, but was not detected above the reported sample quantitation limit.
L The results fall below the Contract Required Quantitation Limit. Results are estimated and are consideredqualitatively acceptable but quantitatively unreliable due to uncertainties in the analytical precision near the limitof detection.
R The sample results are rejected due to serious deficiencies in the ability to analyze the sample and meet qualitycontrol criteria. The presence or absence of the analyte cannot be verified. >.*
UJ The analyte was not delected above the reported sample quantitation !;.«„; ! -•> ever, the reported quantitationlimit is approximate and may or may not represent the actual limit of quantitation necessary to accurately andprecisely measure the analyte in the sample.
J The analyte was positively identified; the associated numerical value is the approximate concentration of theanalyte in the sample.
NJ The analysis indicates the presence of an analyte that has been "tentatively identified" and the associatednumerical value represents its approximate concentration.
NO QUALIFIERS indicate that the data are acceptable both qualitatively and quantitatively.
Table 3-4Results of Enzyme Immunoassay Screening for Toxaphene
Gila River Indian Reservation SiteMaricopa County, Arizona
August 15 & 16, 1996
Sample Location
FS-281
FS-29FS-301
FS-31FS-32FS-331
FS-34FS-35FS-36FS-371
FS-381
FS-39FS-40FS-41FS-42FS-43FS-44FS-45FS-46FS-47FS-48FS-49FS-50FS-51FS-52FS-53FS-54FS-55FS-36FS-57FS-58FS-59FS-60FS-61FS-62FS-63FS-64FS-65
Tentative ToxapheneConcen ration (ppm)
-.0 to 1005 to 20
20 to 100Oto53 to 203 to 20 '5 to 205 to 205 to 205 to 205 to 205 to 205 to 205 to 205 to 20Oto 5O t o 5O t o 5O t o 5O t o 5O t o 5Oto5Oto5Oto5O t o 5O t o 5Oto50 to 5Oto5Oto5Oto5Oto5Oto5Oto 50 to 5Oto 5Oto 5Oto 5
Laboratory ToxapheneResult (ppm)0.370 J /0. 100 J
1.400J
0.390 J
0.160 U0.390 J
(. \
Table 3-4 (Continued)Results of Enzyme Immunoassay Screening for Toxaphene
Gila River Indian Reservation SiteMaricopa County, Arizona
August 15 & 16, 1996
Sample Location
FS-66FS-67FS-68FS-69
FS-701
FS-71FS-72
FS-73FS-74
FS-75FS-76FS-77FS-78FS-79FS-80FS-81FS-82
FS-83FS-84FS-85FS-86FS-87
Tentative ToxapheneConcentration (pp n)
Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5Oto 5
Laboratory ToxapheneResult (ppm)
0.069 J
•
1 - Sample sent for laboratory conformation.
U - Not detected, method detection limit shown.
J » The results are estimated and the data are valid for limited purposes; results arequalitatively acceptable.
Legend
• Soil sampling locationSS-44 Sample location
designation
31' /Toxaphene 'concentration andjduplicateconcentration Iin mg/Kg
SS-09 ^SS-05 SS-01\(250/470) / (190) (350/31 )) J
\ . x ,\ / \ / I
\ ' X 'SS;1§_ lm^B±n ^ /cc ™ X *
Vx Yazzie, Homesite x
URS Gr«in*r, Ine.100 California StreetSan Francisco, CA 94111January 27, 1997
Toxaphene Concentration MapConcentrations in mg/Kg or ppm
Yazzie Homesite AreaGila River Indian Reservation
Phoenix. Arizona
FIGURE
3-7
4.0 Hazard Ranking System Factors
The Hazard Ranking System (HRS) is a scoring system used to assess the relative threat associated
with actual or possible releases of hazardous substances from sites. It is the principal
mechanism the EPA uses to place sites on the National Priorities List (NPL). URSG has evaluated
the HRS factors discussed belo^,, which are relative to this site.
4.1 Sources of Contamination
Sources of contamination at tl ? Gila River Indian Reservation site are limited to contaminated
soil. Analysis of surface oil samples for organophosphate pesticides did not show their
presence. Analysis of surficial soil samples for Organochlorine pesticides showed the presence
of delta hexachlorocyclohexane at up to 12 micrograms per kilogram (|ig/Kg), heptachlor
epoxide at up to 2,900 ug/Kg, endrine at up to 1,700 ug/Kg, endosulfan I at up to 310 ug/Kg,
endosulfan II at up to 1,600 Mg/Kg, endosulfan sulfate at up to 1,600 ug/Kg, gamma chlordane at up
to 3,900 Jig/Kg, methoxychlor at up to 2,500 ug/Kg, endrine at up to 1,700 Mg/Kg, endrin aldehyde
at up to 1,400 ug/Kg, Dieldrin at up to 1,600 ug/Kg, 4.4'-DDE at up to 67,000 Ug/Kg, 4,4'-DDD at
up to 520 ug/Kg, 4,4'-DDT at up to 850 ug/Kg, and Toxaphene at up to 830,000 ug/Kg.
Concentrations of the above-mentioned Organochlorine pesticides are greater than three times
background concentrations. Concentrations of heptachlor epoxide, Dieldrin, 4,4'-DDE, and
Toxaphene were found in excess of their -respectsre :GlgC|f ,Rlak Screening Concentrations
(CRSC). An exposure to a contaminant present at or above the CRSC provides a Y In one million
chance that an individual will develop cancer due to this exposure! Concentrations of heptachlor
epoxide were detected in excess of the Reference Dose Screening Concentration (RfD). The RfD
is an estimate of a daily exposure level of a substance to a human population below which
adverse noncancer health effects are not anticipated. If contaminant concentrations are greater
than the CRSC or RfD benchmark concentrations, and are present at concentrations greater than
three times background concentrations, the HRS assigns "level 1" contamination of resident
individuals. Assigning level 1 contamination of resident individuals increases the HRS score for a
given site. Surface soil sampling indicates that Toxaphene is the most widely distributed
contaminant at the site, with average concentrations of 196,000 ug/Kg within the Yazzie Homesite
area. With the exception of the sample collected at location SS-10, all soil samples collected
from the Yazzie Homesite area were greater than the CRSC for Toxaphene of 580 ug/Kg.
URS Greiner, Ino. Page 57
4.2 Groundwater Pathway
4.2.1 Hydrogeologic Setting
The Gila River Indian Reservation site is located within the Basin and Range geomorphic
province. This province is characterized by fault-block uplifting, graben downthrowing, and
erosional deposition. The site is located in a depositional environment, receiving materials from
South Mountain, a small but typical mer morphic core complex, centered with light-colored
granite and surfaced with a sheared, arched carapace of metamorphic rock. The net annual
precipitation for the Phoenix area is approximately 0.5 inch (25). Surficial soils at the site are
thinly developed and composed of alluvial deposits of sandy clays or clayey sands with some
gravel. The approximate depth to groundw- ter in the site vicinity is 90 feet bgs (26).
The GRIR site is located in the West Salt River Valley subbasin of the Phoenix Active Management
Area, created by the Arizona Groundwater Management Act of 1980 (27). According to the well
log from the Gila Crossing Day School Well, located between 3 and 4 miles from the site, the
subsurface consists of approximately 360 feet of sand and gravel underlain by approximately 560
feet of clay and sandy clay layers with some shale, and a granite bedrock, located approximately
920 feet bgs (28).
4.2.2 Croundwater Targets
There are four drinking water wells located within 4 miles of the site. These drinking water wells
are designated as the District 6 North Well, District 6 South Well, the New Gila Crossing Well, and
the Gila Crossing Day School Well. Wellhead Protection Areas have been established at each of
these wells; however, the site is not located within any Wellhead Protection Area (26).
The District 6 North Well, located approximately 0.75 mile from the site, is the drinking water
well nearest the site. The District 6 South Well is located approximately 1.25 miles from the site.
The District 6 North and District 6 South wells provide drinking water to approximately 2,500
people through a blended water system (26). Both the District 6 North and District 6 South wells
are located hydrologically upgradient of the site (29). The District 6 South Well extends to 620
feet bgs, and is screened from 540 to 615 feet bgs (26). The exact screened interval of the
District 6 North well is not known; however, based on its total depth of 634 feet, it is believed to
have a screened interval similar to thru of the District 6 South Well.
The New Gila Crossing Well and the Gila Crossing Day School Well are located between 3 and 4
miles from the site. The New Gila Crossing Well is screened between 350 to 390 feet bgs and 820
URS Greiner, Inc. Page 58
\to 980 feet bgs (26). The New Gila Crossing Well suppli : drinking water to approximately 2,500
people. The Gila Crossing Day School Well is screened between 905 and 925 feet bgs and
supplies drinking water to approximately 2,500 people (2"). Both the New Gila Crossing Well
and the Gila Crossing Day School Well are located upgradient of the site, based on information
received from the Gila River Indian Community.
Several inactive irrigation wells are also located within 4 miles of the site. One groundwater
sample was collected from an agricultural well located n^ar the airstrip on June 21, 1984 by Mr.
Charles Moses of the Gila River Indian Community Pesticide Program. Analysis of this
groundwater sample did not indicate the presence of pesticides. According to Mr. Pete Overton
of the Bureau of Indian Affairs, samples of groundwater collected from these irrigation wells by
Mr. Lee Ballard have indicated the presence of DDT G'O. Laboratory data sheets were not
available to confirm the presence of DDT.
4.2.3 Groundwater Pathway Conclusions
The groundwater pathway is not the primary pathway of concern at the GRIR site.
Organochlorine pesticides detected at the site sorb readily to soil particles and are not highly
soluble or mobile. Groundwater wells within 4 miles of the site supply drinking water to
approximately 7,500 people.
4.3 Surface Water Pathway
4.3.1 Hydrologic Setting
The GRIR site is located within the Basin and Range geomorphic province. This province is
characterized by fault-block uplifting, graben downthrowing, and erosional deposition. The site
is located in a depositional environment, receiving materials from South Mountain, a small but
typical metamorphic core complex, centered with light-colored granite and surfaced with a
sheared, arched carapace of metamorphic rock. The annual net precipitation for the Phoenix
area is approximately 0.5 inch (25). Surficial soils at the site are thinly developed and composed
of alluvial deposits of sandy clays or clayey sands with some gravel. The approximate depth to
groundwater in the site vicinity is 90 feet bgs (26).
Stormwater flowing from the site travels in a southerly direction through lined and unlined
irrigation ditches. These irrigation ditches terminate approximately 0.75 mile south of the site.
From the end of the irrigation ditches, surface water is assumed to flow as sheet-flow to the
southwest, toward the Gila River, located approximately 2.5 miles from the site. The Gila River is
URS Grciner, Inc. Page
highly managed and flows only after rainfall events. The 2-year, M-hour rainfall for the site
vicinity is approximately 1.5 inches (3D- The site is located in an area above the 500-year
floodplain (32). Groundwater flow at the site is believed to be toward the northwest, based on
State of Arizona Department of Water Resources information (27).
4.3.2 Surface Water Targets
Surface water downstream of the site is not used as a source of drinkir g water, as a fishery, or as
habitat for sensitive environments (33). Surface water downstrean. of the site is not used to
irrigate farmland, water livestock, or as a recreational water body.
4.3.3 Surface Water Pathway Conclusions
The surface water pathway is not a pathway of concern at the GRIR s te. There are no uses of
surface water flowing from the site.
4.4 Soil Exposure and Air Pathways
4.4.1 Physical Conditions
The GRIR site is located in an agricultural/residential area approximately 10 miles southwest of
Phoenix, Arizona. A residential area is located directly east of 51st Avenue, approximately 100
feet from the site. Access to the site is not restricted in any way. There are a few barbed-wire
fences surrounding the site; however, these fences are in a state of disrepair and do not restrict
access to the site. The entire site is approximately 20 acres and is relatively flat. The surface soil
at the site consists of sandy clays with some gravel. The site is sparsely vegetated (34).
As stated in Section 4.1, and detailed in Table 3-2 and Figure 3-7, soil at the GRIR site has been
found to contain concentrations of Toxaphene and other Organochlorine pesticides at amounts
greater then three times background concentrations, and above health-based benchmark
concentrations, including the CRSC and RfD. Of the four samples collected near residences
located east of 51st Avenue, one sample, SS-37, contained Toxaphene concentrations in excess of
the CRSC and greater than three times background concentrations.
4.4.2 Soil and Air Targets
Prior to July 1994, there were three residents located on-site. These residents moved from the
site when they began to have health problems and became concerned about the potential
presence of pesticides at the site. There are currently no residents at the site (34).
URS Grcincr, Inc. Page 40
There are no workers at the site, and the site is not currently used for commercial silviculture,
commercial agriculture, or commercial livestock production. The site does not ptovide habitat
for Federally or State-protected species. The site is used by the local community 35 evidenced
by recent graffiti and trash at the site (34). Areas adjacent to the site consist of native desert flora,
protected by the State of Arizona Desert Protection Act.
There are an estimated 127 people living within 1 mile of the Gila River Indian Reservation site.
Approximately 20 people live within 0.25 mile of the site, and of those 20, approximately five
people live within 200 feet of areas with Toxaphene contamination. Population within 4 miles of
the site is presented in Table 4-1 (2, 35, 36).
Table 4-1Population Within 4 Miles of The GRIR Site
Distance (miles)0 to 0.25
0.25 to 0.50.5 to 11 to 22 to 33 to 4
Total Population
Population201295280475
1,1001,982
4.4.3 Soil Exposure and Air Pathway Conclusions
*
The Soil Exposure Pathway is the primary pathway of concern at the GRIR site. Soil sampling
conducted as part of this Site Inspection indicates the presence of Organochlorine pesticides in
surficial soils at concentrations exceeding background and benchmark concentrations. Air
sampling, conducted in October 1985, did not show the presence of contaminants in ambient air
(22). Prior to July 1994, there were three residents located on-site. Currently, there are
approximately 127 people living within 1 mile of the site, approximately five of which live within
200 feet of areas with Toxaphene contamination.
URS Grcincr, Ino. Page 41
5.0 Emergency Response Considerations
The National Contingency Plan [40 CFR 300.415 (b) (2)1 authorizes the Environmental Protection
Agency to consider emergency response actions at those sites which pose an imminent threat to
human health or the environment. For the following reasons, a referral to the EPA's Region IX
Emergency Response Section does not appear to be necessary:
• The site does not present the risk of fire or explosion.
• The EPA removal action of July 1984 included the excavation and removal of highlycontaminated soil, and the treatment and capping of less-contaminated soils.
• Concentrations of contaminants in soils at the site do not present a significant risk tothe drinking water aquifer because of the depth to the drinking water aquifer, and thecharacteristic of site contaminants to bond strongly to soil particles.
• Hazardous substances are no longer in use, and therefore are no longer being releasedto the environment at the site.
URS Gr«in«r, Ino. Page 42
6.0 Summary
The Gila River Indian Reservation (GRIR) site is located approximately 10 miles southwest of
Phoenix, Arizona. The site occupies approximately 20 acres in a rural area. The site is bordered
on the north by the Gila River Indian Reservation boundary and agricultural land, on the west by a
drainage canal, on the south by a dirt road and agricultural land, and on the east by 51st Avenue.
The site was used by agricultural aviation services (crop dusters) between 1959 and the early
1980s. In 1984, the EPA conducted an emergency response action at the site which included the
relocation of site residents, the removal of wastes from a portion of the site, the chemical and
biological treatment of contaminated soils at a portion of the site, and capping a portion of the
site.
Surficial soil sampling conducted in May and August 1996 has indicated the presence of delta
hexachlorocyclohexane at up to 12 micrograms per kilogram (ug/Kg), heptachlor epoxide at up
to 2,900 ug/Kg, endrine at up to 1,700 Mg/Kg, endosulfan I at up to 310 Mg/Kg, endosulfan II at up
to 1,600 Mg/Kg, endosulfan sulfate at up to 1,600 Mg/Kg, gamma chlordane at up to 3,900 ug/Kg,
methoxychlor at up to 2,500 Mg/Kg, endrine at up to 1,700 Mg/Kg, endrin aldehyde at up to 1,400
Mg/Kg, Dieldrin at up to 1,600 Mg/Kg, 4,4'-DDE at up to 67,000 Mg/Kg, 4,4'-DDD at up to 520
Mg/Kg, 4,4'-DDT at up to 850 Mg/Kg, 'ir>d Toxaphene at up to 830,000 Mg/Kg- Concentrations of
heptachlor epoxide, Dieldrin, 4,4'-DDE, and Toxaphene were detected in amounts greater than
their respective Cancer Risk Screening Concentrations (CRSC). Concentrations of heptachlor
epoxide were detected in excess of the Reference Dose Screening Concentration (RfD). Surface
soil sampling indicates that Toxaphene is the most widely distributed contaminant at the site,
with average concentrations of 196,000 Mg/Kg within the Yazzie Homesite area. With the
exception of the sample collected at location SS-10, all soil samples collected from the Yazzie
•Homesite area were greater than the CRSC for Toxaphene.
The following are pertinent HRS factors associated with the site:
• There are four drinking water wells located within 4 miles of the site, which serveapproximately 7,500 people.
• Shallow groundwater is located approximately 90 feet below ground surface.
• There are an estimated 127 people living within 1 mile of the site.
URS Greiner, Inc. Page 45
n \R ^DIAL SITE ASSESSMENT DECISION - EP iCION IX
sShe Name: Cila River Indian Reservation EPA ID #: AZD981621881
Alias Site Names: None
City: Phoenix County or Parish: Maricopa County State: AZ
Refer to Report Dated: April 23. 1997 Report Type: CERCLA Site Inspection
Report Developed By: URS Greiner. Inc.
DECISION:
GET" 1. Further Remedial Site Assessment under CERCLA (Superfund) is not required because:
ET 1 a. Site does not qualify for further remedial site assessment under CERCLA (No Further Action- NFA) and:
D EPA is retaining this site in CERCLIS because the Federal Superfund program still has aninterest in the site.
D EPA is archiving this site in CERCLIS because it does not warrant Federal Superfund action,or an appropriate Federal Superfund response action has been completed. This meansthat EPA believes no further Federal Superfund response is appropriate. Archived sitesmay be returned to the CERCLIS site inventory if new information necessitating furtherFederal Superfund consideration is discovered.
D 1 b. Site may qualify for further action, but is deferred to: D RCRA D NRC
D 2. Further Assessment Needed Under CERCLA D 2a. (optional) Priority: D Higher D Lower
D 2b. Activity Type: D PA D SI D ESI D HRS EvaluationD Other
DIJUSSION/RATIONALE:
Report Reviewed and Approvand Site Decision Made by:
Project M«nj emen«.A\EPA Form f 9100-3 Rev. O6
Boundary Site Site Investigation Report, GRIG, Arizona. Prepared by the GRIGDepartment of Environmental Quality. April 3, 2002. - this report is currently beingphotocopied in the comm center - 2/23/04.